Conventionally, there has been proposed a parking device of this type that includes a piston, a housing accommodating the piston, a spring that urges the piston in a parking lock execution direction by the elastic force, and a solenoid valve that moves the piston in a parking lock release direction by supplying hydraulic oil from a mechanical pump to a hydraulic oil chamber defined by the piston and the housing (see, for example, Patent Document 1). In this parking device, when moving the piston in the parking lock release direction and maintaining the piston in that state, hydraulic oil is supplied from the mechanical pump to the hydraulic oil chamber via the solenoid valve. On the other hand, when moving the piston in the parking lock execution direction, hydraulic oil is discharged from the hydraulic oil chamber via the solenoid valve.